Wire cable for window regulators of auto mobiles

ABSTRACT

A wire cable for window regulators of automobiles is disclosed. In the wire cable, the core strand has a double-layer twisted strand structure with an F+6+12 element wire structure, and consists of a high-strength synthetic resin filament used as a core element wire (F), six internal element wires primarily twisted around the core element wire to form an internal layer around the core element wire, and twelve external element wires secondarily twisted around the internal layer to form an external layer around the internal layer. Eight external strands, having a single-layer twisted strand structure with a 1+6 element wire structure, are twisted around the core strand to form an 8×7+(F+6+12) element wire structure of the wire cable in cooperation with the core strand. The synthetic resin filament used as the core element wire of the core strand has a diameter slightly larger than that of the internal and external element wires of the core strand. The core strand is also compressed at a compression ratio of 2˜10%, thus bringing its element wires into surface contact with each other in place of point contact. In this wire cable, the element wires of the core strand are not likely to be deformed or broken, thus being improved in its fatigue resistance against a repeated bending action, in addition to improving the productivity of the wire cables.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates, in general, to a wire cable forwindow regulators of automobiles and, more particularly, to a wire cablefor such window regulators, using a highly flexible, high-strengthsynthetic resin filament as the core element wire of its core strand;the core strand being also compressed to deform the cross-section of itselement wires and bring the element wires into surface contact with eachother in place of point contact, thus improving the flexibility of thewire cable, in addition to the fatigue resistance of the wire cablenecessarily enduring a repeated bending action during an operation.

[0003] 2. Description of the Prior Art

[0004] As well known to those skilled in the art, wire cables, used forcontrolling the operation of a variety of machines or implements,necessarily endure a repeated bending action since they continuouslypass over power transmitting rotors, such as sheaves, drums or pulleys,while being tensioned during the operation of said machines orimplements. Therefore, the wire cables for such machines or implementsmust have somewhat high resistance to wear and tear, breakage andfrictional abrasion.

[0005] In the prior art, the strand structures of the wire cables forsuch machines or implements have been typically classified into threetypes: a parallel twisted structure formed by twisting a plurality ofelement wires together into a wire cable, a single-layer twistedstructure formed by twisting a plurality of external element wiresaround a core element wire, and a multi-layer twisted structure formedby twisting a plurality of internal and/or external strands around acore strand. A single-layer annular strand cable is included in themulti-layer twisted cables, and has been preferably and widely used forcontrolling the operation of small-sized machines, such as windowregulators of automobiles.

[0006] The single-layer annular strand cable is produced by twisting aplurality of external strands around one core strand such that theexternal strands form an annular single layer around the core strand. Inthe single-layer annular strand cable, each of the external and corestrands consists of a plurality of element wires having circularcross-sections with similar diameters. The core element wire of eachstrand of such a single-layer annular strand cable may comprise one orthree filaments. Of the two types of strands having one or threefilaments as the core element wire, the strand having one filament asthe core element wire has been more preferably used. In addition, onehemp filament in place of the three filaments has been preferably usedas the core element wire of each strand of the single-layer annularstrand cable.

[0007] The wire cable for window regulators of automobiles is arepresentative example of wire cables, consisting of a plurality ofstrands each having one steel core element wire. The conventional wirecable for window regulators of automobiles has the following structure.

[0008]FIGS. 1a and 1 b are sectional views of conventional wire cablesfor window regulators of automobiles. As shown in the drawings, therepresentative examples of conventional wire cables for windowregulators of automobiles typically have two element wire structures: an8×7+1×19 element wire structure and a 7×7 element wire structure. In theelement wire structure of the wire cable 11 of FIG. 1a, the numeral “8”denotes the number of external strands “7” denotes the number of elementwires in each external strand 11B, “1” denotes the number of core strand11A, and “19” denotes the number of element wires of the core strand11A. In the wire cable of FIG. 1b, the numeral “7” positioned at thefront denotes the number of strands, while the numeral “7” positioned atthe back denotes the number of element wires in each strand.

[0009] That is, in order to produce the double-layer twisted core strand11A of the wire cable 11 having the 8×7 +1×19 element wire structure,six internal element wires are primarily twisted around one core elementwire to form an internal layer around the core element wire. Thereafter,twelve external element wires are secondarily twisted around theinternal layer to form the double-layer twisted strand structure of thecore strand 11A. On the other hand, each single-layer twisted externalstrand 11B of the wire cable 11 is produced by twisting eight internalelement wires around one core element wire to form the single-layertwisted strand structure of the external strand 11B. Eight externalstrands 11B are, thereafter, twisted around the core strand 11A to forma desired wire cable 11 having the 8×7+1×19 element wire structure. Inorder to produce the wire cable 12 having the 7×7 element wirestructure, six internal element wires are twisted around one coreelement wire to form a single-layer twisted strand. After a plurality ofsingle-layer twisted strands, six strands used as external strands 12Bare twisted around one strand used as a core strand 12A, thus forming adesired wire cable 12 having the 7×7 element wire structure.

[0010] Of the two types of wires cables 11 and 12, the wire cable 11 ofFIG. 1a has been typically used for controlling the operation of windowregulators of small-sized automobiles. The wire cable 12 of FIG. 1b hasbeen typically used for controlling the operation of window regulatorsof large-sized automobiles.

[0011] Since the wire cable 12, having the 7×7 element wire structure,is made by twisting six single-layer twisted strands 12B as externalstrands around one single-layer twisted strand 12A, it has a highabrasion resistance. The wire cable 12 is thus preferably used forcontrolling a machine, in which the cable 12 is operated while beingbrought into severe frictional contact with other parts. In addition,the wire cable 12 has a simple strand structure, and so it is not likelyto be broken or deformed in its structure.

[0012] When such a conventional wire cable 12 is used for transmittingpower in a window regulator of an automobile while being wrapped aroundand passing over power transmitting rotors, such as sheaves, drums orpulleys, the wire cable 12 may be easily, undesirably removed from therotors during an operation due to low flexibility of the wire cable. Thewire cable 12 also has a low fatigue resistance due to its lowflexibility, and so the cable 12 may be easily cut or broken during anoperation.

[0013] The wire cable 11, having the 8×7+1×19 element wire structure anddesigned to have improved fatigue resistance, has a double-layer twistedcore strand 11A with a 1+6+12 element wire structure, in place of thesingle-layer twisted core strand 12A with a 1+6 element wire structureof the wire cable 12 having the 7×7 element wire structure. In the wirecable 11, the element wires of the core strand 11A each have a diametersmaller than that of each element wire of the external strands 11B. Thewire cable 11 having the 8×7+1×19 element wire structure thus has a highflexibility and a high fatigue resistance, different from the wire cable12 having the 7×7 element wire structure.

[0014] However, the conventional wire cable 11 having the 8×7+1×19element wire structure undesirably has an excessive number of elementwires of the core strand, in addition to a complex double-layer twistedstrand structure complicating the process of producing the wire cables.Another problem experienced in the wire cable 11 resides in that itscore element wires may be more easily cut or broken during a strandtwisting process, in comparison with the wire cable 12 having the 7×7element wire structure. Such wire cables 11 are thus increased inproportion of defectives produced during a wire cable manufacturingprocess, and so productivity of the wire cables 11 is reduced, with aconcurrent increase in the production cost of the cables 11.

[0015] It is necessary for the wire cable for window regulators ofautomobiles, which necessarily as perform a continuous, dynamic bendingaction during an operation, to have a high flexibility and be free frombreakage or cutting of their core element wires during a strand twistingprocess. It is also necessary to allow the element wires of the corestrand of the wire cable to come into surface contact with each other inplace of point contact, thus making the element wires of the core strandto effectively distribute the external load applied from the externalstrands to the core strand during an operation and preventing unexpectedbreakage or cutting of the element wires of the core strand, andpreventing any deformation of the element wire structure of the corestrand during the operation of the window regulator.

SUMMARY OF THE INVENTION

[0016] Accordingly, the present invention has been made keeping in mindthe above problems occurring in the prior art, and an object of thepresent invention is to provide a wire cable for window regulators ofautomobiles, which uses a highly flexible, highly elastic andhigh-strength filament as the core element wire of its core strand, withthe core and external element wires of the core strand being twisted tocome into surface contact with each other in place of point contact,thus effectively distributing external load applied from the externalstrands to the core strand during an operation.

[0017] In order to accomplish the above object, the present inventionprovides a wire cable for window regulators of automobiles, comprising acore strand and a plurality of external strands twisted around the corestrand, wherein the core strand consists of a highly flexible,high-strength synthetic resin filament used as a core element wire, andsix internal element wires primarily twisted around the core elementwire to form an internal layer around the core element wire, and twelveexternal element wires secondarily twisted around the internal layer toform a double-layer twisted strand structure of the core strand, thecore strand being appropriately compressed to deform the cross-sectionof its element wires and bring the element wires into surface contactwith each other.

[0018] That is, the wire cable of this invention includes a core strandhaving a double-layer twisted is strand structure with an F+6+12 elementwire structure. This core strand consists of a high-strength syntheticresin filament used as a core element wire (F), six internal elementwires primarily twisted around the core element wire to form an internallayer around the core element wire, and twelve external element wiressecondarily twisted around the internal layer to form an external layeraround the internal layer. The wire cable also includes eight externalstrands, which have a single-layer twisted strand structure with a 1+6element wire structure and are twisted around the core strand to form an8×7+(F+6+12) element wire structure of the wire cable in cooperationwith the core strand.

[0019] In the wire cable of this invention, the element wires of thecore strand, except for the core element wire, have the same diameter asthat of the element wires of the external strands. The core element wireof the core strand has a circular cross-section with a diameter largerthan that of each of the internal and external element wires of the corestrand by 1.1˜2.0 times.

[0020] The core element wire of the core strand preferably has adiameter of 0.10˜0.20 mm, and has a tensile strength similar to that ofthe steel element wires of the core and external strands. This coreelement wire of the core strand is selected from high-strength syntheticresin filaments having flexibility and elasticity higher than those ofthe steel element wires of the core and external strands.

[0021] In the present invention, the high-strength synthetic resinfilament used as the core element wire of the core strand may bepreferably made of high-strength thermoplastic resin, such aspolypropylene, polyethylene, polyurethane, or nylon.

[0022] In the wire cable of this invention, the highly flexible, highlyelastic and high-strength synthetic resin filament, used as the coreelement wire of the core strand and having a tensile strength of about50˜70 kgf/mm² similar to that of the steel element wires of the core andexternal strands, acts as a cushioning material capable of absorbingcompression load applied from the external strands to the internal andexternal steel element wires of the core strand during an operation ofthe wire cable. The synthetic resin filament used as the core elementwire thus protects the steel element wires from damage or deformationdue to the compression load, and allows the steel element wires toeffectively endure a repeated bending action during an operation of thewire cable.

[0023] Particularly, when a machine controlling wire cable, such as awire cable for window regulators of automobiles, passes over sheaves orpulleys while being tensioned, the wire cable is inevitably deformed inits cross-section from a circular cross-section to an ovalcross-section, in addition to having a difference in load applied to theelement wires of the strands. Therefore, the conventional wire cable isinevitably deformed in its cross-section when it is used for a lengthyperiod of time. However, the wire cable of this invention is less likelyto be deformed in its cross-section, different from the conventionalwire cables, since the wire cable of this invention uses a highlyflexible, highly elastic and high-strength synthetic resin filament asthe core element wire of its core strand. Therefore, the wire cable ofthis invention is lengthened in its expected life span, and has highresistance to fatigue.

[0024] Prior to twisting the external strands around the core strand inthe process of producing the wire cable of this invention, the corestrand is compressed at a compression ratio of 2˜10%, thus compactingthe core strand.

[0025] When the core strand of this wire cable is compressed asdescribed above, the cross-section of the internal and external steelelement wires of the core strand are deformed from their originalcircular cross-section while coming into surface contact with eachother.

[0026] Due to the surface contact of the internal and external elementwires of the core strand, the entire contact area between the elementwires is increased to uniformly distribute external load applied fromthe external strands to the core strand, thus preventing an undesiredconcentration of load to a part of the element wires. This finallyalmost completely prevents a deformation or breakage of the elementwires, in addition to a deformation in the structure of the core strand.

[0027] As described above, the range of the compression ratio for thecore strand is set to 2˜10% for the following reasons. That is, when thecompression ratio for the core strand is lower than 2%, it is almostimpossible to sufficiently enlarge the contact area between the elementwires of the core strand or accomplish the desired load and frictionalforce distributing effect of the core strand. When the compression ratiofor the core strand exceeds 10%, the contact area between the elementwires of the core strand is excessively enlarged to restrict a relativemovement of the element wires of the core strand, thus undesirablyreducing the flexibility of the core strand.

[0028] In the prior art, some wire cables for window regulators ofautomobiles, compressed at a predetermined compression ratio to improvethe fatigue resistance of the wire cables, have been proposed. However,such a conventional wire cable is produced by compressing the cable atthe external strands after completely twisting the external strandsaround the core strand during a cable producing process. Such acompression process undesirably damages the anticorrosion film coated onthe external element wires of the external strands, thus reducing thecorrosion resistance of the wire cables.

[0029] However, in the wire cable of this invention, the core strand iscompressed prior to the step of twisting the external strands around thecore strand, and so the anticorrosion film coated on the externalelement wires of the external strands is prevented from any damage,different from the conventional wire cables.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

[0031]FIGS. 1a and 1 b are sectional views of conventional wire cablesfor window regulators of automobiles, in which:

[0032]FIG. 1a is a sectional view of a conventional wire cable having an8×7+1×19 element wire structure; and

[0033]FIG. 1b is a sectional view of another conventional wire cablehaving a 7×7 element wire structure; and

[0034]FIGS. 2a and 2 b are views of a wire cable for window regulatorsof automobiles in accordance with the preferred embodiment of thepresent invention, in which:

[0035]FIG. 2a is a perspective view of the wire cable; and

[0036]FIG. 2b is a sectional view of the wire cable.

DETAILED DESCRIPTION OF THE INVENTION

[0037] Reference now should be made to the drawings, in which the samereference numerals are used throughout the different drawings todesignate the same or similar components.

[0038]FIGS. 2a and 2 b are a perspective view and a sectional view of awire cable for window regulators of automobiles in accordance with thepreferred embodiment of the present invention.

[0039] As shown in the drawings, the wire cable 3 of this invention hasone core strand 31 and eight external strands 32 twisted around the corestrand 31. The core strand 31 consists of a high-strength syntheticresin filament 31A used as a core element wire, six internal steelelement wires 31B primarily twisted around the core element wire 31A toform an internal layer around the core element wire 31A, and twelveexternal steel element wires 31C secondarily twisted around the internallayer to form an external layer around the internal layer. This corestrand 31 thus has a double-layer twisted strand structure with anF+6+12 element wire structure.

[0040] On the other hand, the external strands 32, twisted around thecore strand 31, each have a 1+6 element wire structure in a conventionalmanner. That is, in each of the external strands 32, six externalelement wires 32B are twisted around one core element wire 32A, thusforming a single-layer twisted strand structure with a 1+6 element wirestructure. Eight external strands 32 are twisted around the core strand31 to form a desired wire cable 3 having an 8×7+(F+6+12) element wirestructure.

[0041] In the wire cable 3, the synthetic resin filament 31A used as thecore element wire of the core strand 31 has a diameter slightly largerthan those of the internal and external steel element wires 31B and 31C.In such a case, the internal and external element wires 31B and 31C havethe same diameter. In addition, the element wires 32A and 32B of eachexternal strand 32 have the same diameter as that of the internal andexternal steel element wires 31B and 31C of the core strand 31.

[0042] During a process of producing the wire cable 3 of this invention,the core strand 31 is compressed prior to the step of twisting the eightexternal strands 32 around the core strand 31. When the core strand 31is compressed as described above, the diameter of the strand 31 isreduced. In such a case, the internal and external steel element wires31B and 31C of the core strand 31 are changed in their cross-sectionsfrom original circular cross-sections into deformed cross-sections withreduced diameters. Such a compression process of the core strand 31 alsobrings the steel element wires 31B and 31C of the core strand 31 intosurface contact with each other in place of point contact, thusincreasing the contact area between the steel element wires 31B and 31C.

[0043] When the core strand 31 is compressed as described above, thesynthetic resin filament 31A, used as the core element wire of the corestrand 31, is also deformed. That is, since the internal steel elementwires 31B compress the synthetic resin filament 31A during the corestrand compressing process, the flexible and elastic synthetic resinfilament 31A is radially depressed on its external surface at severalportions coming into contact with the wires 31B, and is slightlyexpanded at the other portions between the depressed portions as shownin FIG. 3b. Therefore, it is possible for the synthetic resin filament31A to act as a cushion capable of elastically supporting the internalelement wires 31B, in addition to preventing any interference betweenthe element wires 31B.

[0044] In order to experimentally prove the operational effect of thewire cables of this invention in comparison with conventional wirecables, a test for measuring the fatigue resistance of the wire cableswas carried out, and the measuring results are given in Table 1. In theTable 1, the Examples 1 to 4 embodied the present invention, while theComparative Examples 1 and 2 embodied the conventional wire cables.TABLE 1 Strand diameter Fatigue Diameter of ratio (External CompressionCable Testing wire cable Compression strand/core ratio of core pitchvalue Testing Ex. Structure (mm) ratio* (%) Strand) Strand** (%) (mm)(times) times Com. Ex 1 8 × 7 + 1 × 19 1.530 3.6 56.5% 6.3 12.5 7262 66Com. Ex 2 8 × 7 + 1 × 19 1.545 2.8 57.4% 6.9 12.5 6024 33 Ex 1 8 × 7 +(F + 18) 1.498 4.3 58.4% 9.2 12.5 12170 9 Ex 2 8 × 7 + (F + 18) 1.4994.8 57.8% 8.2 12.5 17821 49 Ex 3 8 × 7 + (F + 18) 1.514 3.8 57.8% 8.212.5 16220 53 Ex 4 8 × 7 + (F + 18) 1.531 3.5 56.5% 6.3 12.5 8855 28${{Compression}\quad {ratio}^{*}} = {\frac{{2 \times \alpha} + \beta - \delta}{{2 \times \alpha} + \beta} \times 100}$

[0045] Compression ratio of core strand${\text{Compression ratio of core}{strand}^{**}} = {\frac{\eta + {\gamma \times 4} - \phi}{\eta + {\gamma \times 4}} \times 100}$

[0046] In the above expressions, α is the diameter of each externalstrand, β is the diameter of the core strand, δ is the diameter of thecompressed wire cable, η is the diameter of the core element wire, γ isthe diameter of each external element wire, and φ is the diameter of thecompressed core strand.

[0047] In the Table 1, the element wire structure of each of Examples 1to 4 is expressed by “8×7+(F+18)”, which is only another expression ofthe aforementioned structure “8×7+(F+6+12)”. That is, since the numeral“18” in the expression “8×7+(F+18)” is resulted from the sum of thenumbers of the internal and external element wires, the term “(F+6+12)”is expressed by the term “(F+18)”.

[0048] In the test, the wire cables of Examples 1 to 4 and the wirecables of Comparative Examples were made using element wires having boththe same diameter and the same tensile strength.

[0049] In addition, the test was performed under the condition that eachwire cable was reciprocated within a distance of 200 mm at a rate ofseven times per minute while being loaded with 280N. During thereciprocating movement of each wire cable, the wire cable was bent usingone drum having a diameter of 30 mm and two ball bearings having adiameter of 19 mm. The test for each wire cable has carried out until atleast one strand was broken or cut.

[0050] From the Table 1, it is easily seen that the fatigue resistanceof the wire cable according to this invention is remarkably improved, incomparison with the conventional wire cables.

[0051] As described above, the present invention provides a wire cablefor window regulators of automobiles. In the wire cable of thisinvention, the core strand is compressed to deform the cross-section ofits internal and external steel element wires from their originalcircular cross-section and bring the element wires into surface contactwith each other while enlarging the entire contact area between theelement wires. Since the wire cable uses a high-strength synthetic resinfilament as the core element wire of its core strand, the wire cable hasa high flexibility, in addition to uniformly distributing the externalload applied from the external strands to the core strand. Therefore,the wire cable has a high resistance to fatigue when the cable passesover sheaves or pulleys while being repeatedly bent.

[0052] Since a highly flexible, highly elastic and high-strengthsynthetic resin filament is used as the core element wire of the corestrand of the wire cable, the wire cable is not likely to be undesirablydeformed in its cross-section or structure. In an operation of the wirecable, external load applied from the external strands to the corestrand is uniformly distributed by the element wires of the core strandwithout being concentrated to a part.

[0053] Due to use of the synthetic resin filament as the core elementwire of the core strand, it is possible to almost completely preventundesired cutting or breakage of the core element wire during a wiretwisting process, different from a conventional core element wire madeof steel. In addition, it is not necessary to use a steel core elementwire having a diameter different from that of the internal and externalsteel element wires of the core strand, different from the conventionalwire cable; and the process of producing the wire cables is simplifiedto improve the productivity of the wire cables. In addition, whendifferently coloring the synthetic resin filaments of the core strandsof wire cables, it is possible for users to easily distinguish the wirecables of one manufacturer from those of another manufacturers.

[0054] Although a preferred embodiment of the present invention has beendescribed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

What is claimed is:
 1. A wire cable for window regulators ofautomobiles, comprising: a core strand having a double-layer twistedstrand structure with an F+6+12 element wire structure, said core strandconsisting of: a high-strength synthetic resin filament used as a coreelement wire (F); six internal element wires primarily twisted aroundsaid core element wire to form an internal layer around the core elementwire; and twelve external element wires secondarily twisted around theinternal layer to form an external layer around the internal layer; andeight external strands having a single-layer twisted strand structurewith a 1+6 element wire structure, said external structure being twistedaround said core strand to form an 8×7+(F+6+12) element wire structureof the wire cable in cooperation with the core strand.
 2. The wire cableaccording to claim 1, wherein said core strand is compressed at acompression ratio of 2˜10%.
 3. The wire cable according to claim 1 or 2,wherein the core element wire, internal element wires and externalelement wires of said core strand are brought into surface contact witheach other.
 4. The wire cable according to claim 1, wherein saidsynthetic resin filament has a diameter larger than that of each of theinternal and external element wires of the core strand by 1.1˜2.0 times.5. The wire cable according to claim 1, wherein said synthetic resinfilament is made of high-strength thermoplastic resin.